Bowstring relay



Aug. 7, 1945. E. u. POWELL 2,381,309

BOWSTRING RELAY Filed June 1o, 1943 wlTNEssEs: I INVENTOR 7% 1. dwarv U. /Dowe/ 7741/. v BY ATTORNEY Patented Aug. 7, 1945 UNITED STATES PATENT OFFICE BOWSTRING RELAY Edward U. Powell, Wilkinsburg, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvaniay Application June10, 1943, Serial No. 490,305.

(Cl. D-87) 16 Claims.

My invention relates to high-speed relays or other electric contact make-andbreak devices. and it has particular relation to electromagnetic relays or contactors operating on the principle of the Ibowstring.

The principal object of my invention is to `'brovide a mechanical relay, as distinguished from a tube-type relay. which shall have a fast operating-speed.

A further object of my invention is to provide a damped relay, particularly a damped relay of the bowstring type, which will avoid diillculties olf-bouncing contacts.

A further object of my invention is to provide a mechanical relay of a novel type in which the mass of the moving parts is quite small in relation to the force which is required to move said parts, so that the speed of operation is very fast.

A more particular object oi my invention is to provide a relay utilizing a ilexible ribbon which is under tension, and which is displaced, at an intermediate point, like a bowstring, in response to the operating force o1 the relay.

A still more specic object of my invention is to provide a novel formof contact-means in connection with the aforesaid exible-ribbontype of relay.

With the foregoing and other objects in view, my invention consists in the` parts, apparatus, combinations, systems, and methods hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:

Figure i. is a diagrammatic side v lew of circuits and apparatus embodying my invention in a very simple form;

Fig'. 2 is a transverse sectional view' thereof on the line lli- H of Fig. l; and

Fis. il is a view similar to Fig. 1, showing a preferred form oi' embodiment of my invention.

The general principle of my relay is illustrated in Figs-l. and 2, in which a rigid bar Il, or other stationary elongated support, is utilized to support a light flexible ribbon 5, or other tensionrnember, which is constantly held under tension, as by means of arspring 6. The thickness of the ribbon 5 is exaggerated in the drawing, for convenience in showing it. Secured to an intermediate portion of the ribbon 5 is an iron or other magnetizable armature 'i'.

In the normal, or deenergized, condition of the relay, the armature 1 is spaced from the poles l and 9 of a stationary electromagnet-'frame II, which is provided with a winding I2 energized from a control-circuit II--I 4. The magnet-poles s and l are normally spaced from the armature 1, at such a distance that the magnet is capable of attracting the armature whenever the magnet is energized with a predetermined value o! current. The attraction of the armature 1 to the magnet-poles 8 and 9 results in displacing the intermediate portion of the ribbon 5, after the manner of a bowstring, as illustrated in dottedV lines in Fig. 1, wherein the magnet 1 is dotted in position against the faces of the pole-pieces 8 and 9.

Any suitable form of electric-contact device may be operated by the mpvement of the ribbon iA or 'other tension member. In the particular form of embodiment of my inventionv shown in Figs. 1 and 2, a more or less conventional type of contact-means is shown, including two movable contacts I5 and I6 which are carried by a light flexible contact-spring I1 carried by the ribbon 5 underneath the armature 1, and two co0perating stationary contacts I8 and I9 which are carried by rigid stationary members or supports 2l and 22. A circuit 232Il, to be controlled, is connected to the stationary contact-members 2l and 22 respectively, so Kthat a circuit is completed from the. conductor '23 to the stationary. contact member 2l-I8, the movable contact I5 which engages the same when the relay is operated, the movable contact-spring I'i. the other movable Contact G6,- and the stationary contact-member l@-22, 'and thence to the conductor 24. l.Any other type et contact-device may be utilized in my novel bowstring type ot reiay.

It Wili be observed that 1i have provided o, special type of spring-mechanism in 'which the efiective mass of the movable is reduced to the very minimum. Since the tlmeconstant of any relay is dependent upon the ratio or the oper-ating force to the mass of the moving parts, itwill be obvious that I have provided a quick-acting mechanical relay. It wili further be noted that I have provided a relay which is extremely slmple and extremely rugged, and experience has shown that it is capable or longecontinued operation without the necessity for adjustment or replacement; while carrying heavy current-burdens.

In Fig. 3, I have illustrated a preferred form of my invention, in which the bendable or ilexible tension-member 25 is a two-part member, one part l'belng underneath thel elongated support 21, while the other part 28 or the tension-member is above the support 21, the two parts 20 and 28 oi' the tension-member being connected by an oscillatable bellcrank or pivoted member 2'! for pulling lengthwise onv one part of the twopart bendable tension-member when an interdisplacing an intermediate portion of the upper part 2l ot the tension-member 2l. Inllig. 3, as in the preceding nsures. this force-applying means is of an electromagnetic type. although I wish it to be understood that, in its broader aspects. my invention is not limited to the use of an electromagnetic operating-force. As shown'in Fig. 3, the intermediate portion oi the upper part 2l of the nexible tension-member carries a magnetizable armature 32 which is adapted to be attracted by a relatively stationary electromagnet l! which may be similar to the armature-andmagnet structure already described in connection with Figs. 1 and 2.

In Fig. 3, I have illustrated two special features which contribute 'importantly to an advantageous use o! my invention. In the first place, the support 21 is so constructed that,

when the relay is in its normal or deenergized position, the upper part n of the flexible tensionmember 2l is ilat against the upper side of the support, so that said upper side of the support constitutes a distributedback-stop for the fiat side of the tension-member. When the tensionmember 2l, particularly the aforesaid upper part Il thereof, is in the form of a flat ribbon, as illustrated, this extended or distributed back-strip,

which is provided by the upper side of the sup-Y pori; 21, produceslvery good air-damping which becomes effective only as the ribbon 2l returns to its normal undisplaced position, when the relay is deenergized after a period of energization. This provides damping at the exact time which is desirable for the purpose of preventing vibration oi' the ribbon, namely, near the very end of the travel'oi' the displaced portion of the ribbon 2l. Different widths of ribbon produce dinerent amounts of damping, so that the vibration can be suitably controlled by this means.

A second useful innovation which I have introduced, in the form of my invention shown in Fig. 3, relates to the particular type of novel contact-device in which the movable contact or.

contacts 34 are carried by the upper side of the upper ribbon 28 at an intermediate point which is displaced from the intermediate point carrying the armature 32. 'I'he stationary contact or contacts 3l are disposed so that, when the relay is operated, the movable contact or contacts Il come into contact with the stationary contact or contacts Il before the armature 32 has reached the stationary electromagnetstructure 3l. Since the armature 32 continues to move until it comes into contact with the contacting portion of the electromagnet 33, the upper ribbon-member 2l bends over the stationary contact or contacts 3l, thus producing a second bend in the ribbon, providing a good wipin! contact, and eliminating the usual contact- Springs (suchl'as the spring I1 in Fig. 2) which must ordinarily be used if one is to avoid having a very critical contact-adjustment.

In operation, when electrical energy is supplied to the electromagnet ll in Fig. 3, the armature I! pulls up the upper ribbon 2l after the manner oi' a bowstring, slightly rocking the bell- Crank or other oscillatable member Il, and pulling longitudinally 'uponthe lower part'll of the assnsoo flexible tensionmember 2l, thus straightening out the lower part and still further compressing the compression-type biasing-spring Il. At an intermediatev point in the movement of the upper ribbon 2l. the stationary contact or contacts "are engaged by the movable contact or contacts I4, and as the armature 32 continues to move toward the stationary electromagnet il a positive contact-pressure is applied at M so as to positively keep the contacts closed, against rebound. A second bend is thus introduced in the upper ribbon 2l, forcibly holding the contacts closed.

When the electromagnet 3l is deenergized, in Fig. 3,' the upper ribbon 2l quickly returns to its normal or deenergized position, after first opening the contacts at 34-35. Vibration of the ribbon is damped by the air which is entrapped between the fiat underside of the ribbon and the fiat top surface of the support 21, just as these two parts come together,A thereby avoiding vibrational or rebounding difficulties.

With my invention, it is possible to adjust the relay so as to have either the same. or different, times for making and breaking contacts. In one application of my invention, I prefer to make the adjustment so as to give the shortest equal opening and closing times. As measured by an oscilloscope, this time is about l/wp of a second. Extended tests have shown that this relay is capable of a very large number of repeated operations, without a single faulty operation, even when carrying relatively heavy currents, and it requires no adjustment whatever during the operation, and produces no contact-bounce which could bc detected by an oscilloscope.

I claim as my invention:

1. A wiping contact make-and-break device having a bowstring type of spring-mechanism comprising a flexible tension-member, means for keeping said tension-member under tension,

force-applying means for displacing a n intermediate portion of the tension-member, and conl tact-means including stationary means interposed in the` path of the tension-member for displacing a second intermediate point therein as the force-applying means approaches the end of its travel.

2. A damped, wiping contact make-and-break device having a bow-string type of springmechanism comprising a flexible flat ribbon for a bendabie tension-member, a distributed backstop for the flat side' of the ribbon, means for keeping said ribbon under tension, force-applying means 4i'or displacing an intermediate portion of the ribbon, the arrangement being such that the ribbon comes into engagement with said backstop Awhen released by said force-applying means, and contact-means including stationary means interposed in the path of the ribbon for displacing a second intermediate point therein as the force-applying means approaches the end of its travel.

3. A contact make-and-break device comprising an elongated substantially rigid support, a two-part bendabie tension-member having its two' parts on opposite sides of said support, an oscillatable member for pulling lengthwise .on one part of the two-part bendabie tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendabie tension-member, force-applying means for 1displacing an intermediate portionlof the other part of said twopart bendable tension-member, and contactmeans operated by the movement of the tensionmember.

4. A contact make-and-break device comprising an elongatedv substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of saidsupport, an oscillatable member for pulling lengthwise ono'ne part o! the two-part bendabletension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between anl intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, lforce-applying means for*` displacing an intermediate'portion of the other part of said twopart bendable tension-member, and contactmeans operated by the movement oi the lastmentioned part of the two-part bendable tensionmember.

5. A contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion oi the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tensionmember, force-applying means for displacing an intermediate portion of the other part of said two-part bendable tension-member, said lastmentioned part of the two-part bendable tensionmember being a iiat ribbon, said support having a portion comprising a distributed back-stop for the iiat side of the ribbon when released by'said force-applying means, and contact-means Operated by the movement of the tension-member.

6. A contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable-.tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, force-applying means for displacing an intermediate portion of the other part of said twopart bendable tension-member, said last-mentioned part of the two-part bendable tensionmember being a 'dat ribbon, said support having a portionv comprising a distributed back-stop for the flat side of the ribbon when released by said force-applying means, and contact-means operated by the movement of the ribbon when the latter is displaced by said force-applying means.

7. A contact make-and-break device comprising an elongated substantially rigid support, a two-part flexible tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, force-applying means for displacing an intermediate portion of the other part of said twopart lbendable 'tension-member. and contactmeans including stationary means interposed in the path of said last-mentioned part of the twopart flexible tension-member for displacing -a second intermediate point therein as the forceapplying means approaches the end of its travel.

8. A contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, force-applying means for displacing an intermediate portion of the other part of said twopart bendable tension-member, said last-mentioned part of the two-part bendable tensionmember being a at flexible ribbon, said support having a portion comprising a distributed backstop for the fiat side of the ribbon when released by Lsaid force-applying means, and contactmeans including stationary means interposed in the path of said ilat ilexible ribbon for displacing a second intermediate point therein as the lforce-applying means approaches the end of its travel.

` 9. An electromagnetically operated wiping contact make-and-break device having a bowstrini! type of spring-mechanism comprising a flexible tension-member, means for keeping said tensionmember under tension, a magnetizable armature carried by an intermediate portion of the tensionmember, a relatively stationary electromagnetmember for attracting said armature and displacing said intermediate portion of the tensionmember` and contact-means including stationary means interposed in the path of the tension-member for displacing a second intermediate point therein as the armature approaches the relatively stationary electromagnet-member.

10. An electromagnetically operated, damped, wiping contact make-and-break device having a bowstring type of spring-mechanism comprising a flexible fiat ribbon for a bendable tension-member, a distributed back-stop for the ilat side of the ribbon, means for keeping said ribbon under tension, a magnetizable armature-- carried by an intermediate portion of the ribbon, a relatively stationary electromagnet-member for attracting said armature and displacing said intermediate portion of the ribbon, the arrangement being such that the ribbon comes into engagement with said back-stop when the armature is released by the relatively stationary electromagnet-member, and contact-means including stationary means interposed in the path of the ribbon for displacing a second intermediate point therein as the armature approaches the relatively stationary electromagnet-member.

l1. An electromagnetically operated contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, a magnetizable armature carried by an intermediate portion of the other part of said two-part bendable tensionmeinber, a relatively stationary electromagnet- ,member for attracting said armature and displacing said other part of said two-part bendable tension-member, and contact-means operated by the movement of the tension-member.

12. An electromagnetically operated contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, a magnetizable armature carried by an intermediate portion of the other part o1' said two-part bendable tensionmember, a relatively stationary electromagnetmember i'or attracting said armature and displacing said other part of said two-part bendable tension-member, and contact-means operated by the movement of the last-mentioned part of the two-part bendable tension-member.

13. An electromagnetically operated contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides oi' said support. an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, a magnetizable armature carried by an intermediate portion of the other part of said two-part bendable tensionmember, a relatively stationary electromagnetmember for attracting said armature and displacing said other part of said two-part bendable tension-member, said last-mentioned part of the two-part bendable tension-member being a at ribbon, said support having a portion comprising a distributed back-stop for the ilat side or the ribbon when said armature is released by the relatively stationary electromagnet-member, and contact-means operated by the movement of the tension-member.

14. An electromagnetically operated contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part oi the two-part bendable tension-member when an intermediate portion oi' the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion oi' one part of said two-part bendable tension-member, a. magnetizable armature carried by an intermediate portion of the pol other part oi said two-part bendable tensionmember, a relatively stationary electromagnetmember for attracting said armature and displacing said other part of said two-part bendable tension-member, said last-mentioned part oi' the two-part bendable tension-member being a ilat ribbon. said support having a portion comprising a distributed back-stop for the flat side of the ribbon when said armature is released by the re1- atively stationary electromagnet-member, and contact-means operated by the movement of the ribbon when the latter is displaced by the attraction of the armature.

15. An electromagnetically operated contact make-and-break device comprising an elongated substantially rigid support, a two-part flexible tension-member having its two parts on opposite sides oi said support, an oscillatable member for pulling lengthwise on one part of the two-part bendable tension-member when an intermediate portion of the other part is displaced, compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part; of said two-part bendable tension-member, a magnetizable armature carried by an intermediate portion of the other part of said two-part bendable tensionmember, a relatively stationary electromagnetmember for attracting said armature and displacing said other part of said two-part bendable tension-member, and contact-means including stationary means interposed in the path of said last-mentioned part of the two-part flexible tension-member for displacing a second intermediate nt therein as the armature approaches the relatively stationary electromagnet-member.

16. An electromagnetically operated contact make-and-break device comprising an elongated substantially rigid support, a two-part bendable tension-member having its two parts on opposite sides of said support, an oscillatable member for pulling lengthwise on one part o1' the two-part bendable tension-member when an intermediate portion of the other part is displaced. compression-spring biasing-means interposed between an intermediate portion of said support and an intermediate portion of one part of said two-part bendable tension-member, a magnetizable armature carried by an intermediate portion oi the other part of said two-part bendable tensionmember, a relatively stationary electromagnetmember for attracting said armature and displacing said other part of said two part bendable tension-member, said last-mentioned part of the two-part bendable tension-member being a iiat flexible ribbon, said support; having a portion comprising a distributed back-stop for the fiat side of the ribbon when said armature is released by the relatively stationary electromagnet-member, and contact-means including stationary means interposed in the path of said at ilexible ribbon for displacing a second intermediate point therein as the armature approaches the relatively stationary electromagnet-mernber.

EDWARD U. POWELL. 

